1. Field of the Invention
The present invention relates to a process for producing bar members for use in walking bar assemblies for continuous casting molds.
2. Description of the Prior Art
FIG. 8 shows a walking bar assembly 10 arranged immediately below a continuous casting mold M and comprising a plurality of bar members 20 arranged side by side along a slab S drawn from the mold M. By link means or the like (not shown), the assembly 10 is repeatedly movable up and down and toward and away from the slab S to lower the slab having a thin solidified shell and a high temperature while supporting the slab on its opposite sides. Each of the bar members 20 is a flat hollow tube having an elongated length of about 5 m and internally formed with a cooling channel or channels extending approximately over the entire length thereof. Cold water is supplied to the channels to cool the bar members themselves and indirectly cool the hot slab S in contact therewith. When the assembly is adapted to guide the slab S in a vertical position toward a horizontal direction immediately below the mold M, the bar members 20 are bent longitudinally along the direction of transport of the slab S.
Heretofore used as such walking bar members has been an elongated steel member 11 having a flat rectangular cross section and cooling water channels 12 formed by drilling as shown in FIG. 9, an assembly of a pair of steel channel members 13, 13 with their side edges opposed to each other and joined together by welds 14 as shown in FIG. 10, and an assembly of two flat steel plates 15, 15 and side wall members 16, 16 interposed therebetween at their side edges and joined to the plates by welds 17 as seen in FIG. 11. However, these walking bar members are cumbersome and costly to make. Bar members having drilled channels have been limited in the diameter of the cooling water channels formed, and the cooling effect achieved by the cold water passing therethrough is not always sufficient. On the other hand, bar members fabricated by welding have incurred problems with respect to the material utilized, such as corrosion resistance and strength of the weld zones, and are liable to bend, warp or otherwise deform during welding or heat treatment conducted before or after welding. Further when such members are made from stainless steel, heat-resistant steel or other special steel having low weldability, it is difficult to assemble the components by welding, so that there are limitations in the materials that are usable.